Sodium phenulacetate (NaPA) has been used for years to treat acute and chronic complications of hyperammonemia from inborn errors of urea synthesis or portal systemic encephalopathy. In 1971, it was suggested that NaPA was a potential therapeutic agent for human cancers. Continuous infusion of NaPA will allow the study of the effects of prolonged depletion of this critical amino acid on B-cells. Currently utilized drugs that work by similar mechanisms, i.e., L-asparaginase, can deplete levels of amino acids for only a short time and are administered intermittently. The fact that L-asparaginase does have some effect, even with these limitations, provides rationale to pursue studies with NaPA. By studying disease such as chronic lymphocytic leukemia (CLL), we can easily follow the effects on the tumor cells with simple peripheral blood and bone marrow samples. The goals of this study are 1) to learn if patients with B-cell malignancies (B-CLL and B-cell non-Hodgkin's lymphoma) respond to intravenous NaPA; and 2) to learn the side effects profile in patients with these malignancies when treated with this schedule of NaPA.